Myanmar's junta gave the US military permission to fly in relief supplies for the survivors of Cyclone Nargis, Thai Supreme Commander Boonsrang Niumpradit told Reuters on Thursday.

'We have helped the Americans to talk to the Myanmar government to allow US planes participating in Cobra Gold to fly humanitarian aid to Myanmar. They just agreed,' he said, referring to joint US-Thai military exercises.

A US embassy official confirmed the decision and Boonsrang said the first flights could leave Thailand within a day or two.

'They were very suspicious that the Americans would do more than just distribute relief supplies, but we helped convince the Burmese to allow the Americans in,' Boonsrang said.

The decision is a surprise given the huge distrust and acrimony between the former Burma's generals and Washington, which has imposed tough sanctions to try to end decades of military rule.

However, international pressure had been building on the junta to throw its doors wide open to an international relief operation for the worst cyclone to hit Asia since 1991, when 143,000 people were killed in neighbouring Bangladesh.

Aid has been barely trickling into one of the world's most isolated and impoverished countries, although experts feared it would be too little to cope with the aftermath of Nargis, which left up to 100,000 feared dead and one million homeless.

Witnesses saw little evidence of a relief effort under way in the hard-hit Irrawaddy delta region.

'We'll starve to death, if nothing is sent to us,' said Zaw Win, a 32-year-old fisherman who waded through floating corpses to find a boat for the two-hour journey to Bogalay, a town where the government said 10,000 people were killed.

 'We need food, water, clothes and shelter.'    

The storm pulverised the delta on Saturday with 190 km (120 mph) winds followed by a massive tidal wave that caused most of the casualties and damage, virtually destroying some villages.

UN officials had earlier complained that an airlift of emergency supplies for the victims was delayed on Thursday, awaiting clearance to land from the military government.

'They need assistance today. They needed it yesterday,' Tony Banbury, Asia regional director of the UN World Food Programme WFP, said in Bangkok.

'They can't wait and they shouldn't be asked to wait until tomorrow and it's crucial that food, water, shelter and medical supplies need to go in right away.'    

Another WFP official said three planes were waiting on tarmacs in Bangkok, Dhaka and Dubai with 38 tonnes of supplies. - Reuters